Upload
gerard
View
22
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Photosynthesis. Energy & Life. Photosynthesis. Plants use the Energy of sunlight to convert Water (H 2 0) and Carbon Dioxide (CO 2 ) into Oxygen (O 2 ) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches. The Photosynthesis Equation. [ Waste product ]. Glucose. - PowerPoint PPT Presentation
Citation preview
1
Photosynthesis
Energy & Life
2
Photosynthesis• Plants use the Energy of
sunlight to convert Water (H20) and Carbon Dioxide (CO2) into Oxygen (O2) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches
The Photosynthesis Equation
3
[Waste product]
4
Glucose• Glucose is a monosaccharide
• C6H12O6
• One Molecule of glucose Stores 90 Times More Chemical Energy Than One Molecule of ATP
5
History of Photosynthesis
7
Early Questions on Plants
Several Centuries Ago, The Question Was:
Does the increase in plant mass come from the air? The soil? The
water?
8
Van Helmont’s Experiment
1643• Planted a seedling
into A pre-measured amount of soil and watered for 5 years.
• Weighed Plant & Soil. Plant- gained 75 kg, Soil- same weight.
• Concluded increase in Mass Came From Water
9
Priestley’s Experiment• Burned candle in Bell
Jar until it went out.• If placed sprig of Mint
in Bell Jar for a few days, candle could be relit and burn.
• Concluded plants released substance (O2) necessary for burning.
1771
10
Ingenhousz’s Experiment
1779
Repeated Priestly experiment with & without sunlight
11
Results of Ingenhousz’s Experiment
• Showed that Priestley’s results only occurred in the presence of Sunlight.
• Light was necessary for plants to produce the “burning gas” or oxygen
12
Julius Robert Mayer 1845
Proposed that plants can convert Light Energy into Chemical Energy
13
Samuel Ruben & Martin Kamen
Used Isotopes to determine that the Oxygen liberated[released] in Photosynthesis comes from water KAMEN
RUBIN
1941
14
Melvin Calvin 1948•First to trace the path that carbon (CO2) takes in forming Glucose•Does NOT require sunlight•Called the Calvin Cycle or Light Independent Reaction•Also known as the Dark Reaction
16
Autotrophs
Organisms that contain chlorophyll and are able to use light energy from the sun to produce their own food.
Plant
Euglena
17
Heterotrophs• Heterotroph
s are organisms that can NOT make their own food
• Heterotrophs can NOT directly use the sun’s energy
18
Importance of ATP
Principal Compound Used To Store Energy In Living Organisms
19
Cells Using Biochemical Energy
Cells Use ATP For:• Active transport• Movement• Photosynthesis• Protein Synthesis• Cellular
respiration• All other cellular
reactions
EVERYTHING!
20
ATP – Cellular Energy• Adenosine Triphosphate• Contains two, high-energy
phosphate bonds• Also contains the nitrogen base
adenine & a ribose sugar
21
Sugar in ADP & ATP• Called ribose• Pentose sugar• Also found in
RNA
22
Releasing Energy From ATP
• ATP provides all of the energy for cell activities
• The high energy phosphate bonds are BROKEN to release energy
• ATP is constantly being used and remade by cells
• The process of releasing ATP’s energy & reforming the molecule is called phosphorylation
23
PhosphorylationEnzyme in thylakoid
membrane called ATP Synthase
As H+ ions passed through thylakoid membrane, enzyme binds them to ADP
Forms ATP for cellular
24
Releasing Energy From ATP
• Adding A Phosphate Group To ADP stores Energy in ATP
• Removing A Phosphate Group From ATP Releases Energy & forms ADP.
Loose
Gain
25
More on ATP• Cells Have Enough ATP
To Last For A Few Seconds
• ATP must constantly be made
• ATP Transfers Energy Very Well
• ATP Is NOT Good At Energy Storage
26
Plant Pigments & Cell Structure
27
Light and Pigments
• Energy From The Sun Enters Earth’s Biosphere As Photons, a light energy unit.
• Visible or ‘White’ Light contains a mixture Of different wavelengths
• Different wavelengths are seen as Different Colors
Sho
rtest
w
avel
engt
hLo
nges
t w
avel
engt
h
28
Pigments• In addition to water, carbon dioxide, and light energy, photosynthesis requires Pigments
• Chlorophyll is the primary light-absorbing pigment in autotrophs
• Chlorophyll is found inside chloroplasts
29
ChlorophyllThere are 2 main
types of chlorophyll molecules:
Chlorophyll aChlorophyll b
A third type, chlorophyll c, is found in dinoflagellates
30
Light wavelength absorbed by pigments
Chlorophyll a absorbsBlue = bestRed = 2nd best
Chlorophyllreflects green
31
Chlorophyll
• Absorbs blue wavelength best and red wavelength 2nd best.
• Does NOT absorb green wavelength, but reflects green wavelength.
• This is why plants look green.
32
Carotenoids
• Plant pigment • Absorbs light energy
best in the yellow, orange and red wavelengths.
• Chlorophyll masks these pigments
33
Color Note
• pigments that absorb all wavelengths of light are black.
• pigments that reflect all wavelengths of light are white.
34
Chlorophyll a•Found in all plants, algae, & cyanobacteria•Makes photosynthesis possible•Participates directly in the Light Reactions•Can accept energy from chlorophyll b
35
Chlorophyll b• Chlorophyll b is an
accessory pigment• Chlorophyll b acts
indirectly in photosynthesis by transferring the light it absorbs to chlorophyll a
• Like chlorophyll a, it absorbs red & blue light and REFLECTS GREEN
36
Leaf Structures• Cuticle- Waxy outer layer• Epidermal Cells – Waxy and rigid
outer cell layer.• Stomata - Openings in the
epidermis that allow gas and water exchange.
• Mesophyll layer- spongy layer of cells within leaf where photosynthesis takes place.
37
Leaf Structure
38
Structure of the Chloroplast
• Double membrane organelle
• Thylakoids – flattened sac that contains photosynthesis pigments. Where light dependent reactions occur.
• Granun (grana-plural) Stack of connected Thylakoid sacks.
• Stroma- Gel-like material around grana.
39
Inside A Chloroplast
40
Light & Pigments• Pigments absorb different
wavelengths of light which “excite” electrons in the plant’s pigments.
• Excited electrons carry the absorbed energy
• Electrons are transported by an electron carrier called NADP+
41
• Occurs across the thylakoid membranes
• Uses light energy• Produce Oxygen from
water• Convert ADP to ATP• Also convert NADP+ into the energy carrier NADPH
Light Dependent Reactions
42
Energy Carrier• NADP+ =Nicotinamide
adenine dinucleotide phosphate
• Accepts 2 high energy electrons and a H+ from the Light Reaction which convert NADP+ into NADPH.
• High energy electrons used to build molecules cell needs like glucose.
43
NADPH
44
Light Dependent Reaction
45
Light Reaction SummaryReactants:• H2O• Light EnergyProducts:• OxygenEnergy to drive Dark Reaction• ATP• NADPH
46
Function of the Stroma• Light Independent reactions occur here
• ATP used to make carbohydrates like glucose
• Location of the Calvin Cycle
47
Light Independent Reaction• Also known as the Calvin
Cycle OR Dark Reaction.• Does not require light.• Occurs in the stroma• Uses ATP and NADPH from
the light-dependent reactions to produce high-energy sugars.
48
Light Independent Reaction
• Uses: ATP & NADPH from light reactions used as energy source
• 6 Atmospheric C02 are used to make sugars like glucose and fructose
• Six-carbon Sugars made during the Calvin Cycle
49
The Calvin Cycle
50
Light Independent Reaction Summary
Reactants:• CO2
• Energy from ATP & NADPHProducts:• ADP • NADP+
• Sugars
51
Factors Affecting the Rate of Photosynthesis
• Amount of available water
• Temperature• Amount of
available light energy
52
Photosynthesis Overview